Many industrial and chemical products have a high viscosity at low temperatures, and it is therefore often difficult to handle quantities of such products contained in drums under cold or cool conditions. Furthermore, it is common to store the above-mentioned products outside of manufacturing plant, and although the interior of the plant may be at a temperature sufficient to lower the viscosity of the product, the rate of heat transfer into the drum or other container may be insufficient to warm the contents quickly if the product is needed urgently.
As a consequence, various means for heating drums have been suggested.
In the known prior art, drums and other such containers have been heated by steam coils or jackets or by radiant electrical heating in order that the contents may be handled at a temperature at which the viscosity of the content is lower than the viscosity at the ambient temperature. It has also been suggested that induction heating could be employed as an alternative to radiant and/or steam heating.
It is found that the cost of constructing a robust induction heater is prohibitive. Known induction heaters suffered from inevitable mishandling during use, which resulted in the exposure of, and damage to, the current carrying windings. This is not only dangerous to the user, but also necessitates replacement of the heater.